1. Field of the Invention
The present invention relates to a double-deck elevator capable of adjusting a spacing in the vertical direction between upper and lower cages, and more specifically, it relates to a double-deck elevator improved so as to adjust the spacing in the vertical direction without causing any impacts or vibrations to each cage.
2. Description of the Related Art
Recently, double-deck elevators having upper and lower cages which respectively arrive on two floors, upper and lower floors, of a building in order to increase the elevator handling capacity in the vertical direction in high-rise buildings have attracted attention.
In many recent super high-rise buildings, the design is improved by providing an open-ceiling entrance hall or lobby on a first floor, where height from the first floor to the ceiling is set to be larger than that between other floors.
A double-deck elevator capable of changing the spacing in the vertical direction between upper and lower cages according to the spacing in the vertical direction between floors has been proposed.
For example, in a conventional double-deck elevator 1 shown in FIG. 8, upper and lower cages 3 and 4 are supported in a vertically movable manner by a cage frame 2 which is hoisted by a main rope R.
Further, right and left screw shafts 5L and 5R extending in the vertical direction are rotatably supported by right and left vertical frames 2a and 2b constituting the cage frame 2.
Drive motors 6R and 6L for rotating the right and left screw shafts 5L and 5R in the forward and reverse directions are disposed on an upper beam 2c constituting the cage frame 2.
In addition, a screw nut 7a of a support frame 7 to support the upper cage 3 is screwed onto an upper screw part 5a of the right and left screw shafts 5L and 5R.
In addition, a screw nut 8a of a support frame 8 to support the lower cage 4 is engaged onto a lower screw part 5b of the right and left screw shafts 5L and 5R.
The upper screw part 5a and the lower screw part 5b of the right and left screw shafts 5L and 5R are threaded in the directions opposite to each other.
Accordingly, when the right and left screw shafts 5L and 5R are driven and respectively rotated in the forward direction by using the right and left drive motors 6R and 6L, the spacing in the vertical direction between the upper and lower cages 3 and 4 can be reduced.
On the other hand, when the right and left screw shafts 5L and 5R are respectively driven and rotated in the directions opposite to each other, the spacing in the vertical direction between the upper and lower cages 3 and 4 can be increased.
In the conventional double-deck elevator 1 shown in FIG. 8, when the spacing in the vertical direction between the upper and lower cages 3 and 4 is not being adjusted, brakes are applied respectively so that the right and left screw shafts 5L and 5R are not rotated, and the spacing in the vertical direction between the upper and lower cages 3 and 4 is not changed.
Accordingly, when adjusting the spacing in the vertical direction between the upper and lower cages 3 and 4, the brakes applied to the right and left screw shafts 5L and 5R, respectively, are released so that the right and left screw shafts 5L and 5R can be freely rotated.
If the number of passengers riding in the lower cage 4 is larger than the number of passengers riding in the upper cage 3, the lower cage 4 becomes heavier than the upper cage 3.
Thus, the biasing force required to rotate the right and left screw shafts 5L and 5R in the reverse direction to move the weight of the lower cage 4 becomes larger than the biasing force required to rotate the right and left screw shafts 5L and 5R in the forward direction to move the weight of the upper cage 3.
Therefore, as soon as the brakes applied to the right and left screw shafts 5L and 5R are released so as to adjust the spacing in the vertical direction between the cages 3 and 4, the right and left screw shaft 5R and 5L are rotated in the directions opposite to each other, impacts and vibrations are caused in the cages 3 and 4, and the passengers in the cages 3 and 4 experience unpleasantness.
Accordingly, a technology has been proposed in which no impacts or vibrations are caused in the cages 3 and 4 even when the brakes applied to the right and left screw shafts 5L and 5R are released when adjusting the spacing in the vertical direction between the cages 3 and 4 by respectively measuring the weight of the cages 3 and 4, and performing control so that a drive torque with a magnitude and direction according to the difference in weight between the cages 3 and 4 is output in advance by the drive motors 6R and 6L.
However, in such a conventional technology, vibration isolating rubber members for elastically supporting the cages 3 and 4 with respect to the support frames 7 and 8 are disposed at four corners below the cages 3 and 4, and the displacement in the vertical direction at the center position of a floor of each cage is measured by corresponding sensors so as to measure the displacement in the vertical direction of the cages 3 and 4 with respect to the support frames 7 and 8.
The weight of the cages 3 and 4 is calculated based on the displacement in the vertical direction of the floor of each cage obtained from each sensor and the elastic constant of the vibration isolating rubber members.
However, the displacement in the vertical direction at the center position of the floors of the cages 3 and 4 does not always necessarily indicate the displacement in the vertical direction of the cages 3 and 4 correctly.
For example, when passengers enter unevenly on the left side of the cage 3, the displacement in the vertical direction on the left side of the cage 3 is large while the displacement in the vertical direction on the right side of the cage 3 is small.
In addition, the total displacement in the vertical direction of the cages 3 and 4 and the displacement in the vertical direction at the center position of a cage floor may be different from each other according to the position of reinforcing members constituting the cage floor.